


Kronos

by makkachinn



Category: Shingeki no Kyojin | Attack on Titan
Genre: Action/Adventure, Alternate Universe - Modern Setting, British!Marco, Eren and Jean are foster brothers, Evil!Marco, Family Secrets, M/M, Mystery, Sassy Detective!Levi, Thriller
Language: English
Status: In-Progress
Published: 2014-01-02
Updated: 2014-03-18
Packaged: 2018-01-07 04:38:18
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,465
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1115596
Author URL: https://archiveofourown.org/users/makkachinn/pseuds/makkachinn
Summary: <blockquote class="userstuff">
              <p>Eren and Jean are non-related brothers who, despite their nonstop fighting all day, live a fairly normal life. This all changes when their father suddenly disappears one day, leaving behind nothing but $50,000 in cash, a cryptic letter, and a business card that eventually leads them to a sassy detective named Levi. And then, well, one thing led to another and the next thing they knew, they were scaling off the Eiffel Tower, escaping the Yakuza, and infiltrating Buckingham Palace.</p>
            </blockquote>





	1. Prologue

**Author's Note:**

> This fic is inspired by the Korean drama 'Fugitive: Plan B' and the book series 'The 39 Clues'. Be prepared for some sass and KindaEvil!Marco.

_Eren is an idiot._

That was what 18-year-old Jean told himself when he opened the refridgerator door and realized there was no more chocolate cake.

 _His c_ hocolate cake.

Out of the hundred things he hated about Eren, eating his cake was definitely number one on the charts. Nobody messed with his cake – nobody.

Deciding to cool himself, the 18 year old marched over to couch and fell back into the plush cushions, grabbing the remote afterwards and turning on the television. The screen flickered on and he flipped the channel to ‘Who Wants to be a Millionaire’ just in time for the first question.

“What is the common name for ‘toxicodendron radicans’?” the host bellowed into the microphone.

Jean snorted. _Poison ivy,_ he mentally answered. _Duh._

But before he could hear or see the contestant’s answer, the doorbell rang. Hearing this Jean raised an eyebrow. Who would come over at this ungodly hour of the night? It could not have been their father, considering he had just departed New York this morning for a 3 week-long business meeting in Houston.

“Eren, get the door!” the bi-colored-haired male shouted before returning to the program.

A few seconds later, a figure appeared at the bottom of the stairs with a look of annoyance. “Because I’m _so_ much closer to it,” the brunette said, each word dripping with sarcasm. They exchanged dirty looks but Eren reluctantly headed to the front door anyway. Feeling victorious, Jean returned to watching his show but it did not take long before he was once more interrupted.

“Jean, get over here!” his brother yelled from the front part of the house.

Said teenager groaned. “Why?”

“Just do it!”

“Ugh, fine, fine! What do you want?”

With another groan, Jean hopped off the couch and dragged himself to where his brother was. He caught sight of Eren looking out the window... but something was wrong.

Jean's gaze softened when he noticed how shocked and scared the younger looked. The last time he saw Eren in this state was when the brunette found out that Jean had almost been ran over by a van a few months ago. Luckily Jean's friend Reiner had pulled him back before anything unfortunate could have happened... but the strangest part was that the van never stopped, as if its intent had been to harm Jean after all.

Realizing this was not the time to be reminiscing the past, Jean was brought back to the present. “What’s wrong?” he asked. “Who’s at the door?”

Eren swallowed the lump in his throat. “The police,” he answered. “It’s the police.”

Suddenly the temperature dropped five degrees. Jean's eyes widened  as he hurried over to the window. “What do you mean the police?”

“The police – they’re at our door.”

Eren was right. Upon sight of the uniformed police vehicle outside their house, Jean rushed to deactivate the house alarm and open the door. There, standing before them, was a tall and bulky policeman.

“Um, is there a problem, officer?” Jean questioned, motioning Eren over.

“Are you Jean Kirschtein and Eren Jaeger, children of Dr. Grisha Jaeger?” the officer questioned, and when they nodded he looked at them with a look of –- was that pity?

"Yeah . . . Why?" asked Eren, dragging on the words longer than they were supposed to be.

The officer took off his hat and held it over his heart. "I'm sorry," he spoke, "but your father's plane crashed earlier this afternoon."

At this, Jean felt his heart drop, and there was no doubt that Eren was experiencing the same shock because it became evident when the younger suddenly flew into a fury of rage.

"W-What do you mean his plane crashed?" he exploded. "Are you saying he's _dead_?"

Jean yanked Eren back, refraining him from attacking the officer. "Hey, calm down! It's not his fault, and getting mad won't make the situation any better!" the older reasoned.

Eren's eyes glowed an eerie green as he glared at Jean but the former reluctantly backed down regardless, realizing his brother was right. Successful in temporarily calming Eren, Jean averted his attention back to the policeman.

"I apologize for my brother," he spoke, ignoring the dirty look directed towards him. "But I have the same question: will Grisha Jaeger not be returning home?"

A look of uneasiness appeared on the officer's features and Jean noted the air palpably tensed. "No, no, It's quite understandable in this situation. The only thing is . . . we aren't sure if Dr. Jaeger will be appearing any time soon whatsoever."

"What do you mean, officer?"

"Upon checking the flight's attendance record, we confirmed that Dr. Jaeger did indeed board the plane; however, after cleaning up the debris and taking roll of all who perished and survived, we found that he was in neither category. We scouted the surrounding area of the crash but there was no still no sign of your father."

Eren gritted his teeth. "What are you trying to say? He just vanished into thin air? Do you think we're stupid?"

"Eren!"

The officer shook his head. "O-Of course not. However, until your father is found, he will be placed on the Missing Persons list. I'm sorry."

The conversation... no, that wasn't the right term. The exchange lasted for another ten minutes before the policeman gave them his best wishes and left. The two brothers soon found themselves sitting at the dinner table in the now cold, empty house. Jean buried his face into his hands and they both sat in silence for the next thirty minutes. The harsh truth had finally reached them.

Their father was gone.

He had vanished.

They were alone.


	2. A Run of Bad Luck

**Summary for the Chapter:**

> This was not a good day.  
> Definitely not a good day.

 

**New York City, New York**

**Central Library**

**5: 00 PM**

Eren had never been the type of person to sit still, especially when it came to the library.

Beside him, his best friend Armin Arlert glanced up from his textbook. "Eren, you should be studying," spoke the 18-year-old blond. "Our test is in two days and I'm ninety-five percent sure you haven't touched your history book until now."

Eren sighed as he glanced down at the dull pages before him. "But there're so many words, and you know I can't focus on one thing for a long time."

"Yeah, I know, I know, it's your ADHD. Here, I'll help you then."

"No Armin, it's o-"

"Let's start with an easy one: what were the major differences in the Roman Republic and the Roman Empire?"

Eren fidgeted. "Uh . . . The first one was a republic and the second was an empire?"

". . . Eren."

"Y-Yeah."

"We learned this in tenth grade. If that’s the only thing you know, you really need to study."

A sigh escaped Eren's lips as his head fell onto the textbook. "I know," he groaned. "But there's just so much history and so little time and it's so boring too. Can I just go home and play some video games? I just bought a new one."

"The military one?"

"Yeah! It's called Recon and it's so cool!"

Armin sighed. "You can but considering the fact that tests count towards a majority of our grade, I don't think you want to fail."

" . . . Huh . . . That's true." Eren then groaned and leaned back in his chair, putting on a determined face. "Alright, let's do this."

It worked for a while, much to Armin's delight. For the past ten years the two had known each other, if it was one thing the blond had found it, it was that Eren rarely concentrated on anything besides video games and sports. That would explain his low grades. On the contrary, thought Armin, Jean was extremely smart. The guy had such a good memory it could be deemed photographic, and in addition, he actually cared about his studies. Not that Armin would tell Eren that or else the latter would throw a fit.

They continued to study and without knowing, seven o’clock came around. It was not until Eren started complaining again that Armin finally noticed the time. “Well,” the blond spoke as he closed his textbook, “we’ve been at this for about two hours. I think that’s a new record for you.”

Eren made a face as he began gathering his things. “Jeez, you make it sound like I have an attention span of a five year old or something.”

“Um . . .  I’m not trying to be mean or anything, but you kinda do.”

“Wow. Thanks.”

Armin gave him a sheepish smile before the duo started for the library exit.

The sun had begun setting approximately an hour ago and the sky was now a blend of dark red and majestic purple. Unlike the brunet, Armin noted the nice afternoon colors.  The time was 7:10 when the two college students exited the building and crossed the parking lot.

“How long does it take to get to our neighborhood again?” questioned Eren.

“About twenty minutes,” Armin replied, leading Eren westwards. “All we have to do is walk down this road, turn right after two blocks, pass through a neighborhood, cross a bridge, turn left, walk another block, and we’ll reach my block.”

Armin waited for a response but he was met with silence.

“. . . Eren?”

There was no reply.

“Eren?”

Still no reply.

“Eren?”

Armin glanced over at the brunet, sighing when he realized the other was squinting ahead and completely ignoring everything he had said.

“That is a really big tree,” he heard his friend mumble.

For the next 10 minutes, the two best friends continued on their way home uneventfully, exchanging light conversations about typical college matters. As they entered the first neighborhood, Armin could not help but finally pull his jacket closer. The February afternoon was quite windy as well as chilly, and though he did not mind the cold, he could not help but notice the sudden drop in temperature. Just as he opened his mouth to make a comment about the New York weather, Eren beat him to it.

“Someone’s following us,” the brunet declared in a hushed tone.

This took Armin by surprise. His eyes widened and he fought the sudden urge to turn around. “A-Are you sure?” he asked.

“Positive,” answered Eren. “It’s a black van that’s been trailing behind us since we left the library.”

“Why are you telling me this now?”

“I didn’t want you to worry... but I bet that once we leave the neighborhood, they’ll make a move.”

Despite the thirty degree weather, sweat drops began to form as Armin nervously attempted to contemplate a plan. Seeing this, Eren shot him a reassuring grin.

“Don’t worry, I already have something in mind,” he informed. “Although it might be a bit, um, unsanitary.”

Armin grimaced.

This was not going to be good.

 

**☩ ☩ ☩**

 

In a black van five meters down the street, a shadow figure hummed quietly as he steered the vehicle, taking precautions to ensure that he remained unseen by the two college students walking ahead. He could not help but smirk as he continued to watch the pair. “Look at them, being so oblivious,” he spoke aloud. “Just wait until they leave the neighborhood -- then we’ll take action.”

A loud yell suddenly erupted from the back of the car, causing the shadowy figure to jump and glance at the rear-view mirror. He caught a glimpse of his patch-covered right eye and scowled when he saw two light-haired men wrestling in the back of the car. “Thomas, Millius, what in the world are you two doing?” he demanded, twisting his neck around to give them a dirty look.

The one known as Thomas grunted. “Millius elbowed me in the face when he put on his ski mask!” he claimed.

“Hey, it was an accident!”

“Yeah right! Was it because I ate your sandwich last week?”

“That's ridiculous! But hey, at least you’ll finally look cool, having an eyepatch like Marco.”

Despite the compliment, the shadowy figure known as Marco furrowed his eyebrows. “Have you both forgotten our mission?” he rebuked.

At this, Thomas and Millius bowed lowly in an ashamed manner. “No, boss!” they responded.

“Then focus!”

“Yes sir!”

Marco turned back and rubbed the temple near his eyepatch in an exasperating manner. “Why am I working with these buffoons?” he muttered to himself and averted his attention back to . . . back to . . .

Wait a minute . . .

Where did . . .

Realization struck Marco and he gritted his teeth, slamming his fist down at the steering wheel. “Curses!” he yelled. “We lost them!”

 

**☩ ☩ ☩**

 

Everything was dark. Eren shifted his body awkwardly in his hiding spot, a large blue trash bin that belonged to a nice two-story house. His hand reached down and carefully pulled out his phone, and he was thankful that the garbage disposal workers had dropped by earlier that day or else he would have been sharing the space with--

He shuddered at the thought and unlocked his phone, lighting the enclosed space.  _Man, would Jean hate to be here_ , he thought, referring to his claustrophobic brother. The brunet then checked the time. _7:22 huh? How long have I been in here? Three minutes? Four? They're probably gone now. I guess it wouldn't hurt to take a peek . . ._

With some difficulty, the 19 year old slowly pushed himself up and gently raised the top of the trash bin, making sure only his eyes were revealed. He carefully surveyed the area for any movement and suspicious vehicles, and once he deemed the area clear, he flung the lid open and leaped out. He then rushed over to the trash bin in the neighboring driveway and knocked twice. "All clear," he informed.

The lid flew open and out emerged a not-so-satisfied but nevertheless safe Armin. "Remind me to never, ever go along with any of your plans again," mumbled the blond.

Eren grinned. "Hey, we lost the stalkers so I should at least get _some_ credit. Besides, at least the garbage truck came by this morning."

"I guess. It must be because luck is always on your side." With the help of his best friend, Armin managed to get out of the unsanitary hiding spot. "Good thing I didn't shower yet," he added.

A small laugh escaped Eren before his expression turned serious. “I wonder who those guys were,” he spoke.

Armin straightened his clothes before looking down the street. “Well whoever they were, they’re gone now. The important thing is that we get home.”

“Yeah . . .“

Armin noticed the troubled look on the brunet’s features. “Eren?”

“Huh?"

“Don’t worry too much -- it’ll just make things worse.”

“Yeah . . . I guess you're right.”

Though he agreed, Eren still could not help but have bad vibes about the black van, as if there was something more hidden under the surface.

 _Did I see ever see it before?_ he asked himself. _Why am I having such a bad feeling about this? I mean . . . my instincts are usually right, so . . ._

He then shook his head. _No, Armin’s right... we should focus on getting back home_.

Fortunately, the rest of the trip was uneventful. Eren dropped off Armin first before continuing down the block. Before he knew it, he was walking up the stone steps to his front door, fishing for the keys in his pocket; however, before he had the chance to retrieve them, a silver Sedan smoothly pulled into the driveway. Eren felt his mood turn sour as he watched a familiar figure exit the car and close the door suavely.

Jean.

Eren shot the bi-colored-haired male a frown as the latter trudged up the front steps smugly. “Well isn’t it a nice surprise to see you waiting for me?” sneered the older.

“Who would want to wait for you?”

Jean ignored him. “Did you just get home? Where’d you go? Finally found someone desperate enough to go on a date with you?”

“Maybe; you know, I would’ve gotten home a lot sooner if I had a car.”

“You would if you didn’t get distracted by something new every five seconds.”

He had a point. . .not like Eren was going to admit that though. “ . . . Shut up and open the door you stupid horseface.”

Hearing his nickname, Jean scowled but proceeded to retrieve the keys anyway. “I told you not to call me that,” he grunted, successfully unlocking the door and entering the house. “Jeez, you really have no self-discipline at a--”

He suddenly froze.

Eren, who had been mumbling something incoherent under his breath, followed blindly. Because he was distracted, he collided face-first into the older’s back, causing him to voice a loud “ow!”

“Dang it, Jean!” he yelled out angrily and swerved around the other. “Is it so hard to just w-- argh!”

His foot knocked into something causing him to propel forward, but before he could fall onto the hard tile floor, his hand shot out and grabbed onto the wall.The brunet looked down to see a fallen lamp stand, the object he had tripped on. He blinked, trying to comprehend what was happening, and when he looked up at Jean his eyes met something else. “What in the . . .”

The living room was trashed. Paper and broken glass littered the floor. All the furniture were flipped and turned upside down, and the paintings and picture frames that once decorated the walls were now scattered on the ground. Cabinet doors were flung open, shelves were cleared, and the bookcase that once stood proudly beside the piano was now emptied and knocked over, sprawling across the ground.

Eren gaped at the scene, his eyes trying to take in everything he saw. A sudden ‘click’ was heard and he jerked around, exhaling in relief when he realized Jean had just locked the front entrance. Eren swallowed the lump in his throat and averted his attention back to the mess that was once called his living room.

“W-What happened?” he stammered.

Jean stared at the chaos, eyes betraying no emotion. A moment of silence full of tension and bewilderment passed before anyone spoke a word.

“Eren,” Jean finally spoke for the first time they entered their house, “we need to talk.”

 

**Notes for the Chapter:**

> For some of you that do not know who Millius is, he's Background-Chan!


	3. Intentions

20 minutes had passed since the two brothers arrived home to utter chaos and now they found themselves in their father's study, staring at the empty spot in the wall where the safety vault had been before the burglary.

"Guess they found what they were looking for," Eren grumbled. "But couldn't they have done it  _without_ trashing the house?"

Jean stood and observed his surroundings, eyes narrowed and brows knitted. "Something's not right," he declared.

Eren made a face. "What?"

"There were at least two people here; that would explain how they carried the safe. I checked earlier -- they came in through the back door. Now if they started from the kitchen, they would have gone to the living room next. Are you getting this, Eren?"

"Uh . . . kind of. Whatever, go on."

"When we were downstairs, did you notice that everything was thoroughly searched?"

Eren blinked and tried to recall the mess downstairs, and though his memory was hazy, he still remembered the scattered books, the broken picture frames, the overturned furniture, the knocked-down bookcase. Now that he thought about it, Jean was right: everything was thoroughly searched.  _Everything._

"Yeah," the brunet replied. "Why?"

"Think about it: why would they trash downstairs but not the study?"

"Because the safe was right there?"

Jean nodded. "Exactly, the safe was right there. All they had to do was come and grab it. Don't you find it weird how Grisha would just leave something valuable in plain sight? He knew it could easily be taken away. That man is overly cautious about every little thing. He would always remind us to wear our seatbelts in the car, to never listen to music while we're on the streets, to always set the house alarm even when it's broad daylight. He taught us how to escape a locked room, how to disarm a robber, how to get out of handcuffs and calculate the amount of air left by using the dimensions of the room. Heck, he even bulletproofed all of the windows, even the cars. If he was always so careful, why would he leave something as important as a safe in plain sight? Knowing him, he would have hidden in somewhere less obvious like a hidden room or secret compartment." Suddenly, Jean's eyes widened and he rushed over to where the safe had been. "That's it!" he suddenly exclaimed.

Eren stared at him in a confused manner. "Wait what? What're you talking about?"

He watched as the other poked his head into the 13" x 13" x 13" space, craning his neck left and right as if searching for something.

"I can't believe I never noticed," Jean said before pulling his head back out. "There's no way Grisha would leave a vault in the open unless it was his intention to."

"Huh? Are you saying he  _wanted_ the vault to be stolen?"

"That's exactly what I'm saying."

"Are you stupid? Why would he want to do that?"

"It didn't make sense to me at first either but I think I figured it out. Listen Eren, I think he knew this was going to happen."

Eren shot him an incredulous look. "Dude, you're crazy. How would he know? If you haven't noticed, he's been gone for five months --  _five months._ "

"Just hear me out first! Don't you find it strange how the burglars looked through  _every single thing?_ They knew they only have a limited amount of time before we returned home yet they took the risk to clear off the whole shelf. Normal burglars wouldn't spare it a second look; they would just head to the study or the bedroom instead. This proves that our burglars were looking for something in particular, something they knew would be well-hidden; but when they saw the safe right there in plain sight, they grabbed it without a second thought and scurried on out. They don't know how careful Grisha really is, how he's always one step ahead in the game. And Grisha knew this. I think that whatever he was really hiding - whatever the burglars were really searching for - is still here, concealed. I think that he believed we would be able to figure out what's going on."

There was a moment of silence as Eren's mind struggled to comprehend the complication of the situation. 

"I . . . I think I get what you're trying to say . . ." he finally spoke.

Jean nodded. "Good. But hey, honestly, don't worry too much 'cause it'll only cloud our judgement. For now, let's just try to figure out what Grisha was really hiding."

"Alright," Eren agreed. "Any ideas?"

Jean averted his attention back to the hollow block in the wall. "Actually, yes," he replied before extending his hand into the hollow area, feeling around slowly. "It may be somewhere around . . . here . . . aha!" 

Eren shifted to get a better view of what was happening. He watched as Jean applied pressure to a certain spot in the roof of the block and his eyes widened when a small compartment slid open, revealing a thick, folded envelope.

Jean cracked a smug grin. "Found it."

Before he could do anything, Eren snatched it out of the older's hand and ripped it open. Immediately, his eyes widened.

"W-Whoa," he stammered. "What-"

Jean peeked over his shoulders and when he realized what was in the envelope, his jaw slacked.

Inside the envelope was a stack of one-thousand dollar bills.

"Are these real?" Eren gasped. "How did he-"

Jean grabbed the envelope and peered inside. He then reached in and plucked out a small card. Curiosity reached its peak as his eyes scanned over its content quickly.

"It's a business card," he announced before flipping it over. "Private Investigator Levi. Hm."

He then handed the card to Eren who accepted it. "What's this doing in the envelope?" asked the latter as he scanned the card.

"I don't know but chances are Grisha wants us to find him. He's giving us clues; he wants us to go on some kind of scavenger hunt." Jean glanced back into the envelope and noticed a white folded sheet of paper, pulling it out as well before unraveling it. "Eren, look at this."

Said boy tore his eyes from the envelope and leaned over to get a better look at the white paper. His eyes slightly widened when he realized what was written.

 

_Dear Eren & Jean,_

_If you have found this letter, it must mean that I am gone. At this time, I am not certain why, how, or by what means, but I know that they will make their move soon. There is something I have kept from you two for a long time and I apologize, but you must continue my work. In this letter is a clue. Find it, search for Levi, and follow the clue to wherever it takes you. Lastly, whatever you do, beware of Kronos._

_Your father,_

_Grisha Jaeger_

 

A moment of silence passed as the two siblings processed the letter. Finally, Eren spoke up. "Well," he spoke, "this is crazy, but if he wants us to find something, then that's what we'll do. You in?"

Jean stared at the envelope, the thousand dollar bills, the letter, his brother. What was this idiot thinking? Was he expecting to barge into a situation without knowing anything?

Jean knew he wasn't like Eren -- no, almost not at all. Unlike the other who was willing to do whatever his father said, Jean needed answers. There were so many things he didn't understand. What was Grisha trying to do? What does he want them to find? Did this have anything to do with his disappearance? Who was Kronos?  _What_ was Kronos?

The bi-colored haired teen felt his head throb from the overload of questions. He wanted to know -- no, he  _needed_ to know. And there was only one way to find out.

Jean nodded. "Alright I'm in," he declared.

The grin that appeared on Eren's face made him give a small smile, and he realized that this was one of those rare times in which they were equals. Kind of.

"First things first though," added the older. "Grisha must have wanted us to find this Levi person because he'll help us out. I'll call and schedule an appointment with him; in the meantime, you go downstairs and start cleaning up. Just looking at that mess makes the room feel stuffy."

At this, Eren made a face. "Wait, why do  _I_ have to clean?"

"Huh?"

"Why don't  _you_ clean while _I_ make the call?"

"Because you don't know how to make an appointment?"

"What? Are you tryna say I'm stupid?"

"I didn't say anything!"

"You were implying it!"

"No I wasn't!"

"Yes, you were!"

"Ugh, Eren, this is not the tim-- _ow_!"


End file.
